A known air-suspension device 101 shown in FIG. 1 includes a valve block 102 that is assigned to a rear axle and contains a central 3/2-way directional control valve 104 for aerating and venting air-spring bellows 106 of the rear axle, and a valve block 108 assigned to a front axle, for aerating and venting air-spring bellows 110 of the front axle.
Central 3/2-way directional control valve 104 of valve block 102 assigned to the rear axle either connects a compressed-air supply 112 to pressure inlets 114 of downstream 2/2-way directional control valves 116, 118, which are each assigned to one vehicle side of the rear axle, and whose pressure outlets are connected, for their part, to air-spring bellows 106 of the rear axle, and to a supply-pressure connection 120 of valve block 108 assigned to the front axle, or connects this supply-pressure connection 120 and pressure inlets 114 of 2/2-way directional control valves 116, 118 to an air vent 26. The two 2/2-way directional control valves 116, 118 either connect rear axle air-spring bellows 106 assigned to them to a pressure outlet 122 of central 3/2-way directional control valve 104 or block such a connection.
Valve block 108 assigned to the front axle likewise contains a 3/2-way directional control valve 124, which, depending on its switching position, either connects its supply-pressure connection 120 to connections 126, 128 of air-spring bellows 110 of the front axle or, in a driving position, interconnects the two connections 126, 128 via a throttle 130 and blocks supply-pressure connection 120.
The 3/2-way directional control valve 124 of valve block 108 assigned to the front axle, central 3/2-way directional control valve 104, as well as the two 2/2-way directional control valves 116, 118 of valve block 102 assigned to the rear axle, take the form of pneumatically pilot-operated solenoid valves, i.e., they are each controlled by a relay valve, which is not shown for reasons of scale and is controlled, for its part, electrically. To this end, pilot-operation connections 132, 133 of these valves are connected to compressed-air supply 112 via pneumatic lines 134, 136; in particular, a pneumatic line 136 runs from compressed-air supply 112 to pilot-operation connection 133 of 3/2-way directional control valve 124 of valve block 108 assigned to the front axle.
Published German patent document DE 101 63 379 describes an air-suspension system having a plurality of bellows, which are selectively connectable to at least one source of pressure via one or more valve configurations. This air-suspension system has a pressure sensor and a pressure-sensing valve configuration, which is provided for selectively connecting the pressure sensor to at least some of the bellows.